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Abstract:

A photorefractive composite, a spatial light modulator and a hologram
display device using the same include at least one carborane compound
expressed as the following Chemical Formulae 1A through 1C:
##STR00001##
wherein the photorefractive composite exhibits photoconductivity and
optical nonlinearity.

2. The photorefractive composite of claim 1, wherein the at least one
carborane compound is at least one compound expressed as the following
Chemical Formulae 2A through 2M: ##STR00021## ##STR00022## where,
Z1 and Z2 are, independently from each other, one selected from
hydrogen atoms, deuterium atoms, halogen atoms, substituted or
non-substituted C1-C20 alkyl groups, substituted or
non-substituted C2-C20 alkenyl groups, substituted or
non-substituted C2-C20 alkynyl groups, substituted or
non-substituted C1-C20 alkoxy groups, substituted or
non-substituted C3-C20 cycloalkyl groups, substituted or
non-substituted C3-C20 cycloalkenyl groups, substituted or
non-substituted C5-C20 aryl groups, substituted or
non-substituted C2-C20 heteroaryl groups, substituted or
non-substituted C5-C20 aryloxy groups, and substituted or
non-substituted C5-C20 aryltio groups, Z1 and Z2 are
the same or different, p and q are integers of 1 through 5, and n is an
integer of 0 through 10.

3. The photorefractive composite of claim 1, wherein the substituted
C5-C60 aryl groups include at least one carborane group.

4. The photorefractive composite of claim 3, wherein the at least one
carborane compound is at least one compound expressed as the following
Chemical Formulae 2N through 2P: ##STR00023## where, Z1 and
Z2 are, independently from each other, one selected from hydrogen
atoms, deuterium atoms, halogen atoms, substituted or non-substituted
C1-C20 alkyl groups, substituted or non-substituted
C2-C20 alkenyl groups, substituted or non-substituted
C2-C20 alkynyl groups, substituted or non-substituted
C1-C20 alkoxy groups, substituted or non-substituted
C3-C20 cycloalkyl groups, substituted or non-substituted
C3-C20 cycloalkenyl groups, substituted or non-substituted
C5-C20 aryl groups, substituted or non-substituted
C2-C20 heteroaryl groups, substituted or non-substituted
C5-C20 aryloxy groups, and substituted or non-substituted
C5-C20 aryltio groups, Z1 and Z2 are the same or
different, p and q are integers of 1 through 5, n is an integer of 0
through 10, Ar1, Ar2, and Ar3 are, independently from each other,
substituted or non-substituted C5-C20 arylene groups, a and b
are integers of 0 to 2, and c is an integer of 1 to 5.

5. The photorefractive composite of claim 1, wherein the at least one
carborane compound is at least one compound expressed as the following
Chemical Formulae 2A through 2C: ##STR00024##

6. The photorefractive composite of claim 4, the carborane compound is at
least one compound expressed as the following Chemical Formulae 3A
through 3D: ##STR00025##

7. The photorefractive composite of claim 1, wherein the at least one
carborane compound is present in the photorefractive composite in an
amount of about 0.1 parts to about 5 parts by weight with respect to 100
parts by weight of the photorefractive composite.

9. The photorefractive composite of claim 1, further comprising; a
photoconductive polymer, wherein the photoconductive polymer is present
in the photorefractive composite in an amount of about 30 parts to about
60 parts by weight with respect to 100 parts by weight of the
photorefractive composite.

11. The photorefractive composite of claim 1, further comprising: a
nonlinear optical chromophore, wherein the nonlinear optical chromophore
is present in the photorefractive composite in an amount of about 20
parts to about 50 parts by weight with respect to 100 parts by weight of
the photorefractive composite.

12. The photorefractive composite of claim 1, further comprising: a
photosensitizer.

13. The photorefractive composite of claim 12, wherein the
photosensitizer is one selected from the group consisting of C60
fullerene, phenyl-C61-butyric acid methyl ester (PCBM),
2,4,7-trinitrofluorenone (TNF),
2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFDM), and a mixture of
these materials.

14. The photorefractive composite of claim 12, wherein the
photosensitizer is present in the photorefractive composite in an amount
of about 0.1 parts to 3 about parts by weight with respect to 100 parts
by weight of the photorefractive composite.

15. The photorefractive composite of claim 12, wherein the
photosensitizer is excitable by a light source having a wavelength in a
range of about 380 nm to about 740 nm.

16. The photorefractive composite of claim 1, further comprising: a
plasticizer.

18. The photorefractive composite of claim 16, wherein the plasticizer is
present in the photorefractive composite in an amount of about 1 part to
20 parts by weight with respect to 100 parts by weight of the
photorefractive composite.

19. The photorefractive composite of claim 1, further comprising: a
photoconductive polymer, wherein an electric conductivity of the
photoconductive polymer increases when the photoconductive polymer
absorbs electromagnetic radiation.

20. The photorefractive composite of claim 1, wherein, a light absorption
region of the at least one carborane compound is in a visible light
region, and the photorefractive composite excludes an additional
photosensitizer.

21. A spatial light modulator (SLM), comprising: a first electrode; a
second electrode corresponding to the first electrode; and a
photorefractive layer between the first and second electrodes, wherein
the photorefractive layer includes at least one carborane compound
expressed as the following Chemical Formulae 1A through 1C: ##STR00026##
where, R1 and R2 are, independently from each other, one
selected from hydrogen atoms, deuterium atoms, halogen atoms, substituted
or non-substituted C1-C30 alkyl groups, substituted or
non-substituted C2-C30 alkenyl groups, substituted or
non-substituted C2-C30 alkynyl groups, substituted or
non-substituted C1-C30 alkoxy groups, substituted or
non-substituted C3-C30 cycloalkyl groups, substituted or
non-substituted C3-C30 cycloalkenyl groups, substituted or
non-substituted C5-C60 aryl groups, substituted or
non-substituted C2-C30 heteroaryl groups, substituted or
non-substituted C5-C30 aryloxy groups, and substituted or
non-substituted C5-C30 aryltio groups, wherein the
photorefractive layer exhibits photoconductivity and optical
nonlinearity.

22. The SLM of claim 21, wherein the at least one carborane compound is
at least one selected from the group consisting of compounds expressed as
the following Chemical Formulae 2A through 2M: ##STR00027##
##STR00028## where, Z1 and Z2 are, independently from each
other, one selected from hydrogen atoms, deuterium atoms, halogen atoms,
substituted or non-substituted C1-C20 alkyl groups, substituted
or non-substituted C2-C20 alkenyl groups, substituted or
non-substituted C2-C20 alkynyl groups, substituted or
non-substituted C1-C20 alkoxy groups, substituted or
non-substituted C3-C20 cycloalkyl groups, substituted or
non-substituted C3-C20 cycloalkenyl groups, substituted or
non-substituted C5-C20 aryl groups, substituted or
non-substituted C2-C20 heteroaryl groups, substituted or
non-substituted C5-C20 aryloxy groups, and substituted or
non-substituted C5-C20 aryltio groups, Z1 and Z2 are
the same or different, p and q are integers of 1 through 5, and n is an
integer of 0 through 10.

23. The SLM of claim 21, wherein the substituted C5-C60 aryl
groups include at least one carborane group.

24. The SLM of claim 23, wherein the at least one carborane compound is
at least one compound expressed as the following Chemical Formulae 2N
through 2P: ##STR00029## where, Z1 and Z2 are, independently
from each other, one selected from hydrogen atoms, deuterium atoms,
halogen atoms, substituted or non-substituted C1-C20 alkyl
groups, substituted or non-substituted C2-C20 alkenyl groups,
substituted or non-substituted C2-C20 alkynyl groups,
substituted or non-substituted C1-C20 alkoxy groups,
substituted or non-substituted C3-C20 cycloalkyl groups,
substituted or non-substituted C3-C20 cycloalkenyl groups,
substituted or non-substituted C5-C20 aryl groups, substituted
or non-substituted C2-C20 heteroaryl groups, substituted or
non-substituted C5-C20 aryloxy groups, and substituted or
non-substituted C5-C20 aryltio groups, Z1 and Z2 are
the same or different, p and q are integers of 1 through 5, n is an
integer of 0 through 10, Ar1, Ar2, and Ar3 are, independently from each
other, substituted or non-substituted C5-C20 arylene groups, a
and b are integers of 0 to 2, and c is an integer of 1 to 5.

25. The SLM of claim 21, wherein the at least one carborane compound is
one of the compounds expressed as the following Chemical Formulae 2A
through 2C: ##STR00030##

27. The SLM of claim 21, further comprising: a nonlinear optical
chromophore, wherein the nonlinear optical chromophore is one selected
from the group consisting of 4-piperidinobenzylidene malononitrile
(PDCST), 2,5-dimethyl-4-(p-nitrophenylazo)anisole (DMNPAA),
2,N,N-dihexyl-amino-7-dicyanomethylidenyl-3,4,5,6,10-pentahydronaphthalen-
e (DHADC-MPN), 4-di(2-methoxyethyl)aminobenzylidene malonotitrile
(AODCST), amino-thienyl-dioxocyano-pyridine (ATOP), fluorinated
cyano-tolane chromophore (FTCN), and diethylamino-nitrostyrene (DEANST),
and a mixture of these materials.

28. The SLM of claim 21, further comprising: a photosensitizer.

29. The SLM of claim 28, wherein the photosensitizer is excitable by a
light source having a wavelength in a range of about 380 nm to about 740
nm.

30. The SLM of claim 28, wherein the photosensitizer is one selected from
the group consisting of C60 fullerene, phenyl-C61-butyric acid
methyl ester (PCBM), 2,4,7-trinitrofluorenone (TNF), and
2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFDM), and a mixture of
these materials.

33. The SLM of claim 21, further comprising: a photoconductive polymer,
wherein an electric conductivity of the photoconductive polymer increases
when the photoconductive polymer absorbs electromagnetic radiation.

34. The SLM of claim 21, wherein, a light absorption region of the at
least one carborane compound is in a visible light region, and the
photorefractive composite excludes an additional photosensitizer.

35. A hologram display device, comprising: a light source unit configured
to irradiate light for recording and reproducing a three-dimensional
image of an object; an input unit configured to input three-dimensional
image information of the object; a display unit including the spatial
light modulator (SLM) according to 21, wherein the display unit is
configured to record the three-dimensional image information of the
object input by the input unit and configured to reproduce the
three-dimensional image of the object by using the light irradiated from
the light source unit; and an optical system configured to transmit the
light irradiated from the light source unit to the input unit and the
display unit.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C.
§119(e) to Korean Patent Application No. 10-2011-0131115, filed on
Dec. 8, 2011, in the Korean Intellectual Property Office, the disclosure
of which is incorporated herein by reference in its entirety.

[0005] In order to realize holograms, studies have been actively conducted
about a spatial light modulator (SLM) that uses a photorefractive
composite. The photorefractive composite is a material simultaneously
having optical nonlinearity and photoconductivity, and a refractive index
of which is periodically spatially modulated (spatial modulation of
refractive index) due to redistribution of charges generated by light
irradiation. The SLM is an apparatus that may modulate intensity and a
phase of a light beam, and may repeatedly record 3D information. However,
current SLMs do not have a sufficient modulation speed to realize a
display. Therefore, there is a need to develop a new photorefractive
composite.

[0013] In example embodiments, the substituted C5-C60 aryl groups may
include at least one carborane group. The at least one carborane compound
may be at least one compound expressed as the following Chemical Formulae
2N through 2P:

##STR00005##

where, Z1 and Z2 are, independently from each other, one selected from
hydrogen atoms, deuterium atoms, halogen atoms, substituted or
non-substituted C1-C20 alkyl groups, substituted or non-substituted
C2-C20 alkenyl groups, substituted or non-substituted C2-C20 alkynyl
groups, substituted or non-substituted C1-C20 alkoxy groups, substituted
or non-substituted C3-C20 cycloalkyl groups, substituted or
non-substituted C3-C20 cycloalkenyl groups, substituted or
non-substituted C5-C20 aryl groups, substituted or non-substituted C2-C20
heteroaryl groups, substituted or non-substituted C5-C20 aryloxy groups,
and substituted or non-substituted C5-C20 aryltio groups, Z1 and Z2 are
the same or different, p and q are integers of 1 through 5, n is an
integer of 0 through 10, Ar1, Ar2, and Ar3 are, independently from each
other, substituted or non-substituted C5-C20 arylene groups, a and b are
integers of 0 to 2, and c is an integer of 1 to 5.

[0014] In example embodiments, the at least one carborane compound may be
at least one compound expressed as the following Chemical Formulae 2A
through 2C:

##STR00006##

[0015] In example embodiments, the at least one carborane compound may be
at least one compound expressed as the following Chemical Formulae 3A
through 3D:

##STR00007##

[0016] In example embodiments, the at least one carborane compound may be
present in the photorefractive composite in an amount of about 0.1 parts
to about 5 parts by weight with respect to 100 parts by weight of the
photorefractive composite.

[0017] In example embodiments, the photorefractive composite may include a
photoconductive polymer, wherein the photoconductive polymer may be one
selected from the group consisting of polyvinylcarbazole (PVK),
polysiloxane carbazole, polyparaphenylenevinylene, polyaniline,
polypyrrole, polyacetylene, polythiophene, polyalkylthiophene,
poly(alkylthiophene), carbazole-substituted polysiloxane (PSX-Cz),
poly(p-phenylene terephthalate) carbazole (PPT-CZ), polyacrylate
triphenylamine (TATPD), derivatives thereof, and a mixture of these
materials.

[0018] In example embodiments, the photoconductive polymer may be present
in the photorefractive composite in an amount of about 30 parts to about
60 parts by weight with respect to 100 parts by weight of the
photorefractive composite.

[0019] In example embodiments, the photorefractive composite may include a
nonlinear optical chromophore, wherein the nonlinear optical chromophore
may be one selected from the group consisting of 4-piperidinobenzylidene
malononitrile (PDCST), 2,5-di methyl-4-(p-nitrophenylazo)anisole
(DMNPAA), 2,N,N-di
hexyl-amino-7-dicyanomethylidenyl-3,4,5,6,10-pentahydronaphthalene
(DHADC-MPN), 4-di(2-methoxyethyl)aminobenzylidene malonotitrile (AODCST),
amino-thienyl-dioxocyano-pyridine (ATOP), fluorinated cyano-tolane
chromophore (FTCN), diethylamino-nitrostyrene (DEANST), and a mixture of
these materials.

[0020] In example embodiments, the nonlinear optical chromophore may be
present in the photorefractive composite in an amount of about 20 parts
to about 50 parts by weight with respect to 100 parts by weight of the
photorefractive composite.

[0021] In example embodiments, the photorefractive composite may further
include a photosensitizer. The photosensitizer may be one selected from
the group consisting of C60 fullerene, phenyl-C61-butyric acid
methyl ester (PCBM), 2,4,7-trinitrofluorenone (TNF),
2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFDM), and a mixture of
these materials. The photosensitizer may be present in the
photorefractive composite in an amount of about 0.1 parts to 3 about
parts by weight with respect to 100 parts by weight of the
photorefractive composite. The photosensitizer may be excitable by a
light source having a wavelength in a range of about 380 nm to about 740
nm.

[0023] In example embodiments, an electric conductivity of the
photoconductive polymer may increase when the photoconductive polymer
absorbs electromagnetic radiation.

[0024] In example embodiments, a light absorption region of the at least
one carborane compound may be in a visible light region, and the
photorefractive composite may exclude additional photosensitizers.

[0025] According to example embodiments, there is provided a spatial light
modulator (SLM) that includes a first electrode, a second electrode
corresponding to the first electrode, and a photorefractive layer between
the first and second electrodes, wherein the photorefractive layer
includes at least one carborane compound expressed as the above Chemical
Formulae 1A through 1C, and the photorefractive layer exhibits
photoconductivity and optical nonlinearity.

[0026] In example embodiments, the at least one carborane compound may be
at least one selected from the group consisting of compounds expressed as
the following Chemical Formulae 2A through 2M:

##STR00008## ##STR00009##

[0027] where, Z1 and Z2 are, independently from each other, one
selected from hydrogen atoms, deuterium atoms, halogen atoms, substituted
or non-substituted C1-C20 alkyl groups, substituted or
non-substituted C2-C20 alkenyl groups, substituted or
non-substituted C2-C20 alkynyl groups, substituted or
non-substituted C1-C20 alkoxy groups, substituted or
non-substituted C3-C20 cycloalkyl groups, substituted or non-substituted
C3-C20 cycloalkenyl groups, substituted or non-substituted C5-C20 aryl
groups, substituted or non-substituted C2-C20 heteroaryl groups,
substituted or non-substituted C5-C20 aryloxy groups, and substituted or
non-substituted C5-C20 aryltio groups, Z1 and Z2 are the same or
different, p and q are integers of 1 through 5, and n is an integer of 0
through 10. In example embodiments, the substituted C5-C60 aryl groups
may include at least one carborane group. The at least one carborane
compound may be at least one compound expressed as the following Chemical
Formulae 2N through 2P:

##STR00010##

where, Z1 and Z2 are, independently from each other, one
selected from hydrogen atoms, deuterium atoms, halogen atoms, substituted
or non-substituted C1-C20 alkyl groups, substituted or
non-substituted C2-C20 alkenyl groups, substituted or
non-substituted C2-C20 alkynyl groups, substituted or
non-substituted C1-C20 alkoxy groups, substituted or
non-substituted C3-C20 cycloalkyl groups, substituted or
non-substituted C3-C20 cycloalkenyl groups, substituted or
non-substituted C5-C20 aryl groups, substituted or
non-substituted C2-C20 heteroaryl groups, substituted or
non-substituted C5-C20 aryloxy groups, and substituted or
non-substituted C5-C20 aryltio groups, Z1 and Z2 are
the same or different, p and q are integers of 1 through 5, n is an
integer of 0 through 10, Ar1, Ar2, and Ar3 are, independently from each
other, substituted or non-substituted C5-C20 arylene groups, a
and b are integers of 0 to 2, and c is an integer of 1 to 5.

[0028] In example embodiments, the at least one carborane compound may be
one of the compounds expressed as the following Chemical Formulae 2A
through 2C:

##STR00011##

[0029] In example embodiments, the SLM may include a photoconductive
polymer, wherein the photoconductive polymer may be one selected from the
group consisting of polyvinylcarbazole (PVK), polysiloxane carbazole,
polyparaphenylenevinylene, polyaniline, polypyrrole, polyacetylene,
polythiophene, polyalkylthiophene, poly(alkylthiophene),
carbazole-substituted polysiloxane (PSX-Cz), poly(p-phenylene
terephthalate) carbazole (PPT-CZ), polyacrylate triphenylamine (TATPD),
derivatives thereof, and a mixture of these materials.

[0030] In example embodiments, the SLM may include a nonlinear optical
chromophore, wherein the nonlinear optical chromophore may be one
selected from the group consisting of 4-piperidinobenzylidene
malononitrile (PDCST), 2,5-dimethyl-4-(p-nitrophenylazo)anisole (DMNPAA),
2,N,N-dihexyl-amino-7-dicyanomethylidenyl-3,4,5,6,10-pentahydronaphthalen-
e (DHADC-MPN), 4-di(2-methoxyethyl)aminobenzylidene malonotitrile
(AODCST), amino-thienyl-dioxocyano-pyridine (ATOP), fluorinated
cyano-tolane chromophore (FTCN), and diethylamino-nitrostyrene (DEANST),
and a mixture of these materials.

[0031] In example embodiments, the SLM may further include a
photosensitizer. The photosensitizer may be excitable by a light source
having a wavelength in a range of about 380 nm to about 740 nm. The
photosensitizer may be one selected from the group consisting of C60
fullerene, phenyl-C61-butyric acid methyl ester (PCBM),
2,4,7-trinitrofluorenone (TNF), and
2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFDM), and a mixture of
these materials.

[0033] In example embodiments, an electric conductivity of the
photoconductive polymer may increase when the photoconductive polymer
absorbs electromagnetic radiation.

[0034] In example embodiments, a light absorption region of the at least
one carborane compound may be in a visible light region, and the
photorefractive composite may exclude additional photosensitizers.

[0035] According to example embodiments, there is provided a hologram
display device including a light source unit configured to irradiate
light for recording and reproducing a three-dimensional image of an
object, an input unit configured to input three-dimensional image
information of the object, a display unit that includes the spatial light
modulator (SLM) wherein the display unit is configured to record
three-dimensional image information of the object input by the input unit
and is configured to reproduce the three-dimensional image of the object
using the light irradiated from the light source unit, and an optical
system configured to transmit the light irradiated from the light source
unit to the input unit and the display unit.

[0036] A carborane compound that may spatially fix electrons is included
in the photorefractive composite, and thus, the photorefractive speed of
the photorefractive composite may be increased. Also, a spatial light
modulator (SLM) having an increased light modulation speed and a hologram
display device having an increased image transformation speed may be
provided by using a photorefractive composite having an increased
photorefractive speed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Example embodiments will be more clearly understood from the
following detailed description taken in conjunction with the accompanying
drawings. FIGS. 1-4 represent non-limiting, example embodiments as
described herein.

[0038] FIG. 1 is a schematic cross-sectional view of a spatial light
modulator (SLM) according to example embodiments;

[0039] FIG. 2 is a schematic cross-sectional view of a hologram display
device according to example embodiments;

[0040] FIG. 3 is a graph of an electric field versus dark conductivity of
photorefractive devices according to example embodiments and a
comparative example; and

[0041] FIG. 4 is a graph of an electric field versus photo conductivity of
photorefractive devices according to example embodiments and a
comparative example.

DETAILED DESCRIPTION

[0042] Various example embodiments will now be described more fully with
reference to the accompanying drawings in which some example embodiments
are shown. However, specific structural and functional details disclosed
herein are merely representative for purposes of describing example
embodiments, and thus may be embodied in many alternate forms and should
not be construed as limited to only example embodiments set forth herein.
Therefore, it should be understood that there is no intent to limit
example embodiments to the particular forms disclosed, but on the
contrary, example embodiments are to cover all modifications,
equivalents, and alternatives falling within the scope of the disclosure.

[0043] In the drawings, the thicknesses of layers and regions may be
exaggerated for clarity, and like numbers refer to like elements
throughout the description of the figures.

[0044] Although the terms first, second, etc. may be used herein to
describe various elements, these elements should not be limited by these
terms. These terms are only used to distinguish one element from another.
For example, a first element could be termed a second element, and,
similarly, a second element could be termed a first element, without
departing from the scope of example embodiments. As used herein, the term
"and/or" includes any and all combinations of one or more of the
associated listed items.

[0045] It will be understood that, if an element is referred to as being
"connected" or "coupled" to another element, it can be directly
connected, or coupled, to the other element or intervening elements may
be present. In contrast, if an element is referred to as being "directly
connected" or "directly coupled" to another element, there are no
intervening elements present. Other words used to describe the
relationship between elements should be interpreted in a like fashion
(e.g., "between" versus "directly between," "adjacent" versus "directly
adjacent," etc.).

[0046] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of example
embodiments. As used herein, the singular forms "a," "an" and "the" are
intended to include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises," "comprising," "includes" and/or "including," if used herein,
specify the presence of stated features, integers, steps, operations,
elements and/or components, but do not preclude the presence or addition
of one or more other features, integers, steps, operations, elements,
components and/or groups thereof.

[0047] Spatially relative terms (e.g., "beneath," "below," "lower,"
"above," "upper" and the like) may be used herein for ease of description
to describe one element or a relationship between a feature and another
element or feature as illustrated in the figures. It will be understood
that the spatially relative terms are intended to encompass different
orientations of the device in use or operation in addition to the
orientation depicted in the figures. For example, if the device in the
figures is turned over, elements described as "below" or "beneath" other
elements or features would then be oriented "above" the other elements or
features. Thus, for example, the term "below" can encompass both an
orientation that is above, as well as, below. The device may be otherwise
oriented (rotated 90 degrees or viewed or referenced at other
orientations) and the spatially relative descriptors used herein should
be interpreted accordingly.

[0048] Example embodiments are described herein with reference to
cross-sectional illustrations that are schematic illustrations of
idealized embodiments (and intermediate structures). As such, variations
from the shapes of the illustrations as a result, for example, of
manufacturing techniques and/or tolerances, may be expected. Thus,
example embodiments should not be construed as limited to the particular
shapes of regions illustrated herein but may include deviations in shapes
that result, for example, from manufacturing. For example, an implanted
region illustrated as a rectangle may have rounded or curved features
and/or a gradient (e.g., of implant concentration) at its edges rather
than an abrupt change from an implanted region to a non-implanted region.
Likewise, a buried region formed by implantation may result in some
implantation in the region between the buried region and the surface
through which the implantation may take place. Thus, the regions
illustrated in the figures are schematic in nature and their shapes do
not necessarily illustrate the actual shape of a region of a device and
do not limit the scope.

[0049] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which example
embodiments belong. It will be further understood that terms, such as
those defined in commonly used dictionaries, should be interpreted as
having a meaning that is consistent with their meaning in the context of
the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.

[0051] A photorefractive composite according to example embodiments
includes a photoconductive polymer, a nonlinear optical chromophore, and
a carborane compound.

[0052] The photoconductive polymer is a kind of polymer, the electric
conductivity of which is increased when it absorbs electromagnetic
radiation. The electromagnetic radiation includes light (e.g., visible
light, ultraviolet rays, and infrared rays). The photoconductive polymer
changes a spatial ratio between electrons and holes by moving charges
generated in a photorefractive composite due to the light irradiation,
and thus, may induce an electric field in the photorefractive composite.

[0053] The photoconductive polymer may include, for example, a carbazole
unit or a triphenyl amine unit, but is not limited thereto. The
photoconductive polymer may include polyvinylcarbazole (PVK),
polysiloxane carbazole, polyparaphenylenevinylene, polyaniline,
polypyrrole, polyacetylene, polythiophene, poly(alkylthiophene),
carbazole-substituted polysiloxane (PSX-Cz), poly(p-phenylene
terephthalate) carbazole (PPT-CZ), polyacrylate triphenylamine (TATPD),
derivatives thereof, a mixture of these materials, or a copolymer of
these materials.

[0054] The content of the photoconductive polymer in a photorefractive
composite may be in a range between 30 parts and 60 parts by weight based
on 100 parts by weight of the photorefractive composite.

[0055] The nonlinear optical chromophores generate a difference of spatial
refractive index by an electric field induced in a photorefractive
composite.

[0057] The nonlinear optical chromophore in a photorefractive composite
may be in a range from about 20 parts to about 50 parts by weight with
respect to 100 parts by weight of the photorefractive composite.

[0058] A carborane compound that includes a plurality of boron, which is
an electron-deficient atom, has high electron affinity. Thus, a carborane
compound may readily trap electrons. A difference of spatial distribution
of holes and electrons are generated in a photorefractive composite when
electrons are well trapped in the photorefractive composite, and
accordingly, photorefractive modulation speed may be increased, and also,
a photorefractive effect may be increased due to the reduction of a dark
current.

[0059] A carborane compound may absorb light, and a wavelength region of
light to be absorbed may be controlled by controlling a conjugation
length of the carborane compound. The conjugation length of a carborane
compound may be controlled by changing a substitution group. For example,
when a conjugation length of a substitution group is increased, a light
absorption region of a carborane compound may be in a visible light
region. When a light absorption region of a carborane compound is in a
visible light region, an additional photosensitizer may not be used in
the photorefractive composite because the carborane compound may function
as a photosensitizer that generates charges in a photorefractive
composite.

[0060] The carborane compound may be one of the compounds expressed as
Chemical Formulae 1A through 1C.

[0062] The terminology "substituted A" in the expression of "substituted
or non-substituted A (A is an arbitrary substitution group)" denotes that
at least one hydrogen atom in A is substituted by a group expressed as a
deuterium atom, a halogen atom, a hydroxyl group, a cyano group, a nitro
group, an amino group, a hydrazine, a hydrazone, a carboxyl group or a
derivative of a salt thereof, a sulfonic acid group or a derivative of a
sulfonate, a phosphoric acid group or a derivative of a phosphate, a
C1-C20 alkyl group, a C2-C20 alkenyl group, a
C2-C20 alkynyl group, a C1-C20 alkoxyl group, a
C3-C20 cycloalkyl group, a C3-C20 cycloalkenyl group,
a C5-C20 aryl group, a C5-C20 aryloxy group, a
C5-C20 aryltio group, a C3-C20 heteroaryl group, a
group expressed as N(Q1)(Q2), and a group expressed as
Si(Q3)(Q4)(Q5). Here, the Q1 through Q5 may be,
independently from each other, hydrogen atoms, deuterium atoms, halogen
atoms, hydroxyl groups, cyano groups, amino groups, nitro groups,
carboxyl groups, C1-C20 alkyl groups, C2-C20 alkenyl
groups, C2-C20 alkynyl groups, C1-C20 alkoxy groups,
C3-C20 cycloalkyl groups, C3-C20 cycloalkenyl groups,
C5-C20 aryl groups, C5-C20 aryloxy groups, or
C5-C30 aryltio groups, or C2-C30 heteroaryl groups.

[0063] For example, the carborane compound may be one of the compounds
expressed as Chemical Formulae 2A through 2P, but is not limited thereto.

[0065] The plural numbers of Z1 and Z2 may be the same or different, p and
q are integers of 1 through 5, and n is an integer of 0 through 10.

[0066] Ar1, Ar2, and Ar3 may be, independently from each other,
substituted or non-substituted C5-C20 arylene groups, a and b may be
integers of 0 to 2, and c may be an integer of 1 to 5.

[0067] More specifically, the carborane compound may be one of the
compounds expressed as Chemical Formulae of 2A through 2C, but is not
limited thereto.

##STR00017##

[0068] Also, the carborane compound may be one of the compounds expressed
as Chemical Formulae of 3A through 3C, but is not limited thereto.

##STR00018##

[0069] The content of the carborane compound in a photorefractive
composite may be in a range from 0.1 parts to about 5 parts by weight
with respect to 100 parts by weight of the photorefractive composite.

[0070] A photorefractive composite according to example embodiments may
include a photoconductive polymer, a nonlinear optical chromophore, a
carborane compound, and a photosensitizer.

[0071] The photoconductive polymer, the nonlinear optical chromophore, and
the carborane compound are as described above, and thus, descriptions
thereof are not repeated.

[0072] The photosensitizer may generate electrons and holes by being
excited by a light source having a specific wavelength, for example,
visible light. The photosensitizer may be, for example, C60
fullerene, phenyl-C61-butyric acid methyl ester (PCBM),
2,4,7-trinitrofluorenone (TNF), or
2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFDM).

##STR00019##

[0073] In the example embodiments, the photoconductive polymer may be
included in a photorefractive composite in a range from about 20 parts to
about 50 parts by weight with respect to 100 parts by weight of the total
photorefractive composite. The nonlinear optical chromophore may be
included in a photorefractive composite in a range from about 20 parts to
about 50 parts by weight with respect to 100 parts by weight of the total
photorefractive composite. The carborane compound may be included in a
photorefractive composite in a range from about 0.1 parts to about 5
parts by weight with respect to 100 parts by weight of the total
photorefractive composite. The photosensitizer may be included in a
photorefractive composite in a range from about 0.1 parts to about 3
parts by weight with respect to 100 parts by weight of the total
photorefractive composite.

[0074] A photorefractive composite according to other example embodiments
may include a photoconductive polymer, a nonlinear optical chromophore, a
carborane compound, a photosensitizer, and a plasticizer.

[0075] The photoconductive polymer, the nonlinear optical chromophore, the
carborane compound, and the photosensitizer are as described above, and
thus, descriptions thereof are not repeated.

[0076] The plasticizer increases the degree of freedom of materials of a
photorefractive composite by reducing a glass transition temperature of
the photorefractive composite. Thereby, the plasticizer increases an
orientational enhancement effect of the photorefractive composite.
Accordingly, the photorefractive efficiency of the photorefractive
composite increases due to the orientational enhancement effect.

[0078] In example embodiments, the photoconductive polymer may be included
in a photorefractive composite in a range from about 30 parts to about 60
parts by weight with respect to 100 parts by weight of the total
photorefractive composite. The nonlinear optical chromophore may be
included in a photorefractive composite in a range from about 20 parts to
about 50 parts by weight with respect to 100 parts by weight of the total
photorefractive composite. The carborane compound may be included in a
photorefractive composite in a range from about 0.1 parts to about 5
parts by weight with respect to 100 parts by weight of the total
photorefractive composite. The photosensitizer may be included in a
photorefractive composite in a range from about 0.1 parts to about 3
parts by weight with respect to 100 parts by weight of the total
photorefractive composite. The plasticizer may be included in a
photorefractive composite in a range from about 1 part to about 30 parts
by weight with respect to 100 parts by weight of the total
photorefractive composite.

[0079] Hereinafter, a space light modulator (SLM) according to example
embodiments will now be described.

[0080] FIG. 1 is a schematic cross-sectional view of an SLM according to
example embodiments.

[0081] Referring to FIG. 1, an SLM 100 may include a first electrode 10, a
second electrode 30 facing the first electrode 10, and a photorefractive
layer 20 interposed between the first electrode 10 and the second
electrode 30. The first electrode 10 may be formed of a material
including Au, Al, ITO, or IZO, but is not limited thereto. The second
electrode 30 may be formed of the same material used to form the first
electrode 10.

[0082] As described in the previous example embodiments, the
photorefractive layer 20 may be formed of a photorefractive composite
that includes a photoconductive polymer, a nonlinear optical chromophore,
and a carborane compound.

[0083] When coherent light having the same wavelength is irradiated onto
the photorefractive layer 20, charges are generated at a portion where
constructive interference occurs. Thus, an internal electric field is
generated by the charges. The internal electric field changes a
refractive index of the photorefractive layer 20, and a diffraction
grating structure is formed in the photorefractive layer 20. The
diffraction grating formed in an SLM has three-dimensional image
information. Thus, when a reference beam is irradiated onto the SLM, a
three-dimensional image is displayed around the SLM.

[0084] In the example embodiments, the redistribution speed of charges
according to the change of light irradiation is increased because a
photorefractive composite having a carborane compound is used in the
photorefractive layer 20. Thus, the photorefractive speed is increased,
and accordingly, the light modulation speed is increased.

[0085] A hologram display device according to example embodiments will now
be described.

[0086] FIG. 2 is a schematic cross-sectional view of a hologram display
device according to example embodiments.

[0087] Referring to FIG. 2, a hologram display device 200 may include a
light source unit 210, an input unit 220, an optical system 230, and a
display unit 240.

[0088] The light source unit 210 generates a laser beam to be used for
providing, recording, and reproducing three-dimensional image information
of an object in the input unit 220 and the display unit 240.

[0089] The input unit 220 inputs three-dimensional image information of an
object to be recorded in the display unit 240 in advance. The input unit
220 may input, for example, three-dimensional image information of an
object such as intensity and phase of light in each space to an
electrically addressed liquid crystal SLM 221. At this point, an input
beam 212 may be used.

[0090] The optical system 230 may include a mirror, a polarizer, a beam
splitter, a beam shutter, and a lens. The optical system 230 may divide a
laser beam 211 generated from the light source 210 into the input beam
212 sent to the input unit 220, a recording beam 213, a reference beam
214, an erasing beam 215, and a reading beam 216 that are transmitted to
the display unit 240.

[0091] The display unit 240 may receive three-dimensional image
information of an object from the input unit 220 and may record it in a
hologram plate 241 configured by an optically addressed SLM, and may
reproduce a three-dimensional image of the object. At this point,
three-dimensional image information may be recorded through interference
between the recording beam 213 and the reference beam 214. The optically
addressed SLM of the hologram plate 241 may use the SLM 100 described
above. Three-dimensional image information of an object recorded in the
hologram plate 241 may be reproduced to a three-dimensional image by a
diffraction pattern generated from the reading beam 216. The erasing beam
215 may be used for rapidly restoring the formed diffraction grating.
Meanwhile, the hologram plate 241 may be moved to a location between an
input point and a reproducing point of a three-dimensional image.

[0092] Because the SLM 100 described above is used in the optically
addressed SLM of the hologram plate 241, the hologram display device 200
according to example embodiments may have an increased image modulation
speed as a result of a rapid optical modulation speed.

[0093] Also, the photorefractive composite and the SLM 100 described above
may be applied to the hologram display device 200 as well as various
types of hologram display devices.

Example Embodiment 1

[0094] A photorefractive composite solution was made by resolving
PVK:PDCST:ECZ:PCBM: Chemical Formula 2A (o-carborane,Aldrich) with a
weight ratio of 49.4:30:20:0.5:0.1 in a toluene solvent. At this point, a
weight ratio of the total constituent (PVK:PDCST:ECZ:PCBM: Chemical
Formula 2A (o-carborane, Aldrich)) with respect to the toluene solvent
was 4:1.

[0095] The photorefractive composite solution was filled between two ITO
electrodes separated 100 μm by a spacer. Afterwards, a photorefractive
device having a photorefractive layer between the two electrodes was
formed by removing the toluene solvent through evaporation.

Example Embodiment 2

[0096] A photorefractive device was formed by the same method of Example
Embodiment 1 except that carborane compound of Chemical Formula 3B was
used instead of o-carborane (Chemical Formula 2A).

Example Embodiment 3

[0097] A photorefractive device was formed by the same method of Example
Embodiment 1 except that carborane compound of Chemical Formula 3D was
used instead of o-carborane (Chemical Formula 2A).

Comparative Example 1

[0098] A photorefractive device was formed through the same process used
in the Example Embodiment 1 except for use of the carborane compound.

[0099] The ratio of compositions of the photorefractive composites of the
Example Embodiments 1 and 2 and the Comparative Example 1 are summarized
in Table 1.

[0101] FIG. 3 is a graph of dark conductivity versus electric fields of
the photorefractive devices according to Example Embodiment 1-3 and the
Comparative Example 1.

[0102] The dark conductivity versus the electric field characteristics of
FIG. 3 were obtained by measuring electrical conductivity while a voltage
is applied to the photorefractive devices under a condition that light is
not entering.

[0103] Referring to FIG. 3, the photorefractive device of Example
Embodiment 1 has the lowest dark conductivity and the dark conductivity
of the photorefractive device of Example Embodiment 1-3 have lower dark
conductivity than that of the photorefractive device of the Comparative
Example 1. This is assuming that the carborane compound effectively traps
electrons due to its high electron affinity, and thus, reduces a current.
Also, it is assumed that, because the dark conductivity is low, the
efficiency of the photorefractive device is increased.

[0104] FIG. 4 is a graph of photo conductivity versus electric fields of
the photorefractive devices according to Example Embodiments 1-3 and the
Comparative Example 1.

[0105] The result of the photo conductivity versus electric field
characteristics of FIG. 4 was obtained under a condition that a He--Ne
laser having a wavelength of 633 nm at 13 mW is irradiated to the
photorefractive device.

[0106] Referring to FIG. 4, the photo conductivities of the
photorefractive devices according to Example Embodiments 2-3 are the
highest and those of the photorefractive devices of Example Embodiment 1
and the Comparative Example 1 are nearly similar to each other.

[0107] From the above, it can be known that the conductivity
characteristics of the photorefractive devices of example embodiments are
superior to those of the known photorefractive devices.

[0108] The foregoing is illustrative of example embodiments and is not to
be construed as limiting thereof. Although a few example embodiments have
been described, those skilled in the art will readily appreciate that
many modifications are possible in example embodiments without materially
departing from the novel teachings. Accordingly, all such modifications
are intended to be included within the scope of the disclosure as defined
in the claims. Therefore, it is to be understood that the foregoing is
illustrative of various example embodiments and is not to be construed as
limited to the specific embodiments disclosed, and that modifications to
the disclosed embodiments, as well as other embodiments, are intended to
be included within the scope of the appended claims.

Patent applications by Chil-Sung Choi, Suwon-Si KR

Patent applications by Gae-Hwang Lee, Hwaseong-Si KR

Patent applications by Jae-Eun Jung, Seoul KR

Patent applications by Kyu-Young Hwang, Ansan-Si KR

Patent applications in class Spatial, phase or amplitude modulation

Patent applications in all subclasses Spatial, phase or amplitude modulation